34 TROPICAL NATURE, AND OTHER ESSAYS. 



tlie sky, looks as delicate as that of the sensitive 

 mimosa. 



Forest-trees of Low Groivth. — The great trees we 

 have hitherto been describing form, however, but a 

 portion of the forest. Beneath their loftv canopy there 

 often exists a second forest of moderate-sized trees, whose 

 crowns, perhaps forty or fifty feet high, do not touch 

 the lowermost branches of those above them. These are 

 of course shade-loving trees, and their presence effectually 

 prevents the growth of any young trees of the larger 

 kinds, until, overcome by age and storms, some monarch 

 of the forest falls down, and, carrying destruction in its 

 fall, opens up a considerable space, into which sun and 

 air can penetrate. Then comes a race for existence among 

 the seedlings of the surrounding trees, in which a few 

 ultimately prevail and fill up the space vacated by their 

 predecessor. Yet beneath this second set of medium- 

 sized forest-trees there is often a third undergrowth of 

 small trees, from six to ten feet high, of dwarf palms, of 

 tree-ferns, and of gigantic herbaceous ferns. Coming to 

 the surface of the ground itself we find much variety. 

 Sometimes it is completely bare, a mass of decaying 

 leaves and twigs and fallen fruits. More frequently it 

 is covered with a dense carpet of selaginella or other 

 lycopodiacese, and these sometimes give place to a 

 variety of herbaceous plants, sometimes with pretty, but 

 rarely with very conspicuous flowers. 



Flowering Trunks and their Probable Cause. — 

 Among the minor but not unimjDortant peculiarities that 

 characterise these lofty forests, is the curious way in 

 which many of the smaller trees have their flowers 

 situated on the main trunk or larger branches instead 



